Distractors
          It is a two-way system, pumping lymph in and out of the heart
          Is made up of contractile tissue, whereas the heart is made of smooth muscle fibers
          Is made of smooth muscles, whereas the heart is made of contractile tissue
              Key
              Is a one-way system, pumping lymph back to the heart
          Question
              How is the lymphatic drainage system different than the cardiovascular system?